/*
 * Copyright (C) 2011 Google Inc.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.inject.spi;

import com.google.inject.Binder;
import com.google.inject.Binding;
import com.google.inject.Injector;
import com.google.inject.internal.util.StackTraceElements;

import java.lang.reflect.Member;

/**
 * A combination of a {@link Dependency} and the {@link Binding#getSource()
 * source} where the dependency was bound.
 * 
 * @author sameb@google.com (Sam Berlin)
 * @since 4.0
 */
public final class DependencyAndSource {
    private final Dependency<?> dependency;
    private final Object source;

    public DependencyAndSource(Dependency<?> dependency, Object source) {
        this.dependency = dependency;
        this.source = source;
    }

    /**
     * Returns the Dependency, if one exists. For anything that can be referenced
     * by {@link Injector#getBinding}, a dependency exists. A dependency will not
     * exist (and this will return null) for types initialized with
     * {@link Binder#requestInjection} or {@link Injector#injectMembers(Object)},
     * nor will it exist for objects injected into Providers bound with
     * LinkedBindingBuilder#toProvider(Provider).
     */
    public Dependency<?> getDependency() {
        return dependency;
    }

    /**
     * Returns a string describing where this dependency was bound. If the binding
     * was just-in-time, there is no valid binding source, so this describes the
     * class in question.
     */
    public String getBindingSource() {
        if (source instanceof Class) {
            return StackTraceElements.forType((Class) source).toString();
        } else if (source instanceof Member) {
            return StackTraceElements.forMember((Member) source).toString();
        } else {
            return source.toString();
        }
    }

    @Override
    public String toString() {
        Dependency<?> dep = getDependency();
        Object source = getBindingSource();
        if (dep != null) {
            return "Dependency: " + dep + ", source: " + source;
        } else {
            return "Source: " + source;
        }
    }
}